U.S.|Val Fitch, Who Discovered Universe to Be Out of Balance, Is Dead at 91

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Val Fitch, Who Discovered Universe to Be Out of Balance, Is Dead at 91

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Val Fitch in 1980, the year he shared the Nobel Prize in Physics. The research that led to his winning discovery was conducted at the Brookhaven National Laboratory.CreditCreditWilliam Sauro/The New York Times

Val Fitch, who shared the 1980 Nobel Prize in Physics for work that revealed a surprising imbalance in the laws of nature and helped explain why the collision of matter and antimatter has not destroyed everything in the universe, died on Thursday at his home in Princeton, N.J. He was 91.

Princeton University, where he was a longtime professor, announced his death.

One finding of modern physics is that every elementary particle on nature’s menu has an evil-twin antiparticle with equal and opposite charge. Upon contact the two annihilate. In experiments in 1964 at the Brookhaven National Laboratory on Long Island, Dr. Fitch and James Cronin, who shared the Nobel Prize with him and is now at the University of Chicago, found that matter and antimatter obeyed slightly different laws of physics.

One of the possible consequences of this, physicists say, is that if you could run the history of the universe — or any experiment — backward, like a movie in rewind, the laws of physics might not be quite the same. The finding contradicted a principle that had been a bedrock of science since Galileo.

Samuel Ting, a Nobel winner and professor at the Massachusetts Institute of Technology, called the work for which Dr. Fitch won his Nobel some of “the most important in the 20th century.” The experiment moreover suggested a way in which matter and antimatter could have avoided mutual destruction in the early universe, leaving a residue that could evolve into stars, galaxies and life.

As Michael Turner, a cosmologist at the University of Chicago wrote in an email, “We now believe this tiny difference led to us!”

Val Logsdon Fitch was born on March 10, 1923, in Merriman, Neb., in the remote Sandhills region in the north of the state. He was the youngest of three children of a cattle rancher, Fred Fitch, and a schoolteacher, the former Frances M. Logsdon. After his father was injured in a horse-riding accident, the family moved 30 miles west to Gordon, Neb., where his father worked in insurance and Val Fitch graduated from high school in 1940 as valedictorian.

After two and a half years at Chadron State College in northern Nebraska, he was drafted and sent to Los Alamos, N.M., to work as a technician on the Manhattan Project. He wound up helping design the detonator for the atomic bomb that was tested at Alamogordo and later dropped on Nagasaki, Japan.

He also met and married Elise Cunningham, a secretary in the lab. She died in 1972. In 1976 he married Daisy Harper. She survives him, as does a son, Alan, from his first marriage; a half sister, Judi Singleton; three stepchildren; eight step-grandchildren; and two step-great-grandchildren. Another son from his first marriage, John, died in 1987.

Dr. Fitch stayed at Los Alamos for three years, happily rubbing elbows with famous physicists. “I observed that the most accomplished experimentalists were also the ones who knew most about electronics and electronic techniques,” he recalled in his Nobel autobiography. He resolved to follow their example.

In this his upbringing on a ranch was an advantage, his son, Alan, said. “He had a preternatural affinity for machines,” Mr. Fitch recalled.

After finishing his undergraduate degree at McGill University in Montreal, Dr. Fitch earned a Ph.D. at Columbia University under James Rainwater, who went on to receive the Nobel in physics in 1975. In his thesis research, Dr. Fitch found that atomic nuclei were only half as big as physicists had thought. He later joined the Princeton faculty.

At the Brookhaven National Laboratory, where he did research, he became friendly with Dr. Cronin during long nights playing bridge while waiting for the lab’s particle accelerator, the Cosmotron, to get running.

He realized that a new detector that Dr. Cronin had built, called a spark chamber spectrometer, would be perfect for an experiment on unstable subatomic particles known as K mesons, which a Yale physicist, Robert Adair, had suggested had weird properties.

Dr. Fitch and Dr. Cronin wrote a two-page proposal and, with two colleagues, James Christenson and René Turlay, set up their experiment in a cramped space in the middle of a new accelerator, the Alternating Gradient Synchrotron. They referred to the space as Inner Mongolia; they had to climb over magnets to get to it.

“We were largely left alone,” Dr. Fitch said in 1980. “We did our own thing, and no one came around and asked any questions. We just sat there and watched the mesons go by.”

In a couple of years they had their answer, and the results shook physics. In about 50 cases, the mesons decayed in a way that was forbidden if nature did not discriminate between matter and antimatter. As Dr. Cronin later explained it in an email, the mesons decayed about 0.3 percent faster into a configuration that included the antiparticle of an electron, called a positron, than they did into one that included an electron.

In that slight difference was a powerful message about the cosmos. Stewart Smith, a Princeton professor and vice-president of the Princeton Plasma Physics Laboratory, called the result “revolutionary.”

“People tried to find other explanations,” he said.

Dr. Cronin remembered thinking, “This is pretty fundamental stuff about the symmetry of time,” and that it probably had something to do with cosmology.

But as Dr. Smith pointed out, there was no consensus about the universe at that time. It was only a year later, when radio astronomers discovered incontrovertible evidence that the universe had begun in a Big Bang, that the issue of how matter and antimatter survived mutual suicide became a burning issue.

In 1967, Andrei Sakharov, the Russian dissident and physicist, put all the pieces together — including the kind of discrepancy that Dr. Fitch and Dr. Cronin had discovered — in a list of conditions that would allow matter to survive the Big Bang.

Dr. Fitch spent the next decade following up on his famous experiment, and experiments at accelerators in California and Japan have documented the effect to high precision. To the disappointment of scientists, however, the amount of discrepancy so far discovered is not enough, by a factor of more than a billion, to explain the preponderance of matter in the universe today.

Following Dr. Fitch and Dr. Cronin’s lead, physicists and cosmologists are still searching for the right ingredient to put into Dr. Sakharov’s formula.

“There has to be some really ingenious proposal for cosmic data,” Dr. Smith said.

Dr. Fitch’s friends and colleagues described him as a modest, warm man who loved the outdoors, sailing every summer in Nova Scotia.

He took pleasure in working quickly and informally in small groups, compared with the armies of thousands that today run experiments at places like CERN, the European Organization of Nuclear Research in Geneva. His son said that Dr. Fitch had once noted that his prizewinning research took only two years from proposal to results and only four people to accomplish. “The field today has no resemblance to what I did,” Alan Fitch recalled his father saying.

In his autobiographical statement for the Nobel committee, Dr. Fitch wrote: “At any one time there is a natural tendency among physicists to believe that we already know the essential ingredients of a comprehensive theory. But each time a new frontier of observation is broached we inevitably discover new phenomena which force us to modify substantially our previous conceptions. I believe this process to be unending, that the delights and challenges of unexpected discovery will continue always.

“It is highly improbable, a priori, to begin life on a cattle ranch and then appear in Stockholm to receive the Nobel Prize in Physics.”

But then again, he said, thinking of his good fortune with family, friends, teachers and colleagues, it didn’t seem so improbable at all.

A version of this article appears in print on , Section B, Page 15 of the New York edition with the headline: Val Fitch, Who Helped Discover Flaw in Symmetry of Universe, Dies at 91. Order Reprints | Today’s Paper | Subscribe